What procedure can be used to reduce the rate of scale formation on the heating surfaces of a flash evaporator while still maintaining the desired rate of distillate production?

Correct Answer: Option C — Chemically treating the incoming feed water.

Scale formation is primarily caused by the precipitation of calcium and magnesium salts. Chemically treating incoming feed water with anti-scalants or sequestering agents inhibits crystal growth on heating surfaces. This allows the evaporator to maintain high heat transfer rates and distillate production without frequent shutdowns for cleaning.